ISA T1000 PLUS - F<< Threshold and Drop-Off; Trip and Drop-Off Timing

DOC. MIE91093 Rev. 1.34 Page 52 of 145
frequency, and take note of the timing T1. Compute tmax as
80% of T1.
Set the Save function, and Timed test, as follows.
Test control > Fault injection > Timed > tmax (RET)
Save > Confirm at trip > ESC
Select ON; increase the frequency starting from a value less
than F>>. If the relay trips within tmax, pressing the multi-
function knob tripping values can be saved; if not, the test
goes OFF with no message. In this instance, select ON again
until you find the trip. Confirm save results pressing the multi-
function knob, and proceed.
NOTE: stored value is the frequency as the relay trips. This
corresponds to the relay threshold only if the frequency did
not change very much while the relay timing elapsed;
however, for this threshold the timing is short, so the
measurement is accurate.
Next, we find the drop-off threshold for F>>. From the trip
frequency above, slowly decrease the frequency; as the relay
resets, pressing the multi-function knob tripping values can
be saved.
1.6.6. F<< Threshold and drop-off
Now we find the threshold F<<. The procedure is the same as
for F>>: measure T1 and T2, then compute tmax = 0.8*T1,
and set the timed test to find F<<.
1.6.7. Trip and drop-off timing
Now we can measure trip timings, following the F-t curve with
as many points as desired.
Pre-adjust the first test frequency (either more than F> or less
than F<). Select ON+TIME: as the relay trips, test goes OFF;
pressing the multi-function knob tripping values can be saved.
The TRIP LED (43) turns on and parameters at trip are
displayed until ON or ON+TIME are selected. Confirm save
results pressing the multi-function knob, and proceed with
other test frequencies, until all points to be tested are
measured.